England could face a third wave of coronavirus if ministers fail to "get the balance right" with restrictions, Britain's Foreign Secretary has said while trying to persuade Conservative party rebels to back the tier system.
Dominic Raab refused to rule out a third national lockdown if there is another spike in cases in the new year, saying only that the UK government was "doing everything we can to avoid that".
But he sought to win over his Conservative colleagues who are critical of the three-tier system ahead of a crunch Commons vote on the measures on Tuesday when MPs could reject the plan.
Mr Raab insisted the restrictions - which will place swathes of England under stringent rules - are necessary to "bear down" on the pandemic and keep the country out of a national lockdown.
But he said tiers would be downgraded in areas where the virus is in retreat, telling Sky TV: "We are starting with a more restrictive approach than previously with the localised approach.
"But that allows us to ease up when we are confident the virus is going down and stabilised. There's a review every two weeks."
Mr Raab said that, with testing, "those two things are the crucial bridge to that light at the end of the tunnel in the spring".
He also said there was a "risk" of a third spike in case numbers "if we don't get the balance right".
Asked whether there would be another national lockdown if people fail to comply with the rules, Mr Raab said: "We're doing everything we can to avoid that."
His comments came after Boris Johnson wrote to Conservative MPs offering them another chance to vote on the restrictions early next year, saying the legislation will have a "sunset of February 3".
In a bid to head off a rebellion, the Prime Minister also said that at the first review of the measures on December 16 he would move areas down a tier where there is "robust evidence" that coronavirus is in sustained decline.
The vote after Christmas will determine whether the tier system stays in place until the end of March.
Australian Associated Press